The first step to solve a quadratic equation that's set to zero is to factor the quadratic equation:

a² + 4a + 3 = 0
(a + 1)(a + 3) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (a + 1) or (a + 3) must equal zero:

If (a + 1) = 0, a must equal -1
If (a + 3) = 0, a must equal -3

So the solution is that a = -1 or -3

Parallel lines are lines that share the same slope (steepness) and therefore never intersect. A transversal occurs when a set of parallel lines are crossed by another line. All of the angles formed by a transversal are called interior angles and angles in the same position on different parallel lines equal each other (a° = w°, b° = x°, c° = z°, d° = y°) and are called corresponding angles. Alternate interior angles are equal (a° = z°, b° = y°, c° = w°, d° = x°) and all acute angles (a° = c° = w° = z°) and all obtuse angles (b° = d° = x° = y°) equal each other. Same-side interior angles are supplementary and add up to 180° (e.g. a° + d° = 180°, d° + c° = 180°).

The perimeter of a triangle is the sum of the lengths of its sides:

p = x + y + z
p = 13cm + 10cm + 10cm = 33cm

Angles around a line add up to 180°. Angles around a point add up to 360°. When two lines intersect, adjacent angles are supplementary (they add up to 180°) and angles across from either other are vertical (they're equal).

The entire length of this line is represented by AD which is AB + BD:

AD = AB + BD